We present a novel direction based shortest path search algorithm to guide
evacuees during an emergency. It uses opportunistic communications (oppcomms) with
low-cost wearable mobile nodes that can exchange packets at close range of a few to some
tens of meters without help of an infrastructure. The algorithm seeks the shortest path to exits
which are safest with regard to a hazard, and is integrated into an autonomous Emergency
Support System (ESS) to guide evacuees in a built environment. The algorithm proposed
that ESSs are evaluated with the DBES (Distributed Building Evacuation Simulator) by
simulating a shopping centre where fire is spreading. The results show that the directional
path finding algorithm can offer significant improvements for the evacuees.